cromer



Dec. 8, 1964 c. F. CROMER 3,160,726

DOUBLE-BREAK CIRCUIT INTERRUPTERS OF THE GAS-BLAST TYPE WITH VENTEDINTERMEDIATE CONTACTS Filed Jan. 16, 1961 3 Sheets-Sheet 1 1 3 cu iaijfl I i I 5N1? 1 l u ii 3x. U-

B X J 0i .9' INVENTOR Charles F. Cromer ATTORNEY Dec. 8, 1964 c. F.CROMER 3,150,726

DOUBLE-BREAK CIRCUIT INTEIRRUPTERS OF THE GAS-BLAST TYPE WITH VENTEDINTERMEDIATE CONTACTS Filed Jan. 16, 1961 5 Sheets-Sheet 2 Dec. 8, 1964c. F. CROMER 3,

DOUBLE-BREAK CIRCUIT INTERRUPTERS OF THE GAS-BLAST TYPE WITH VENTEDINTERMEDIATE CONTACTS Filed Jan. 16, 1961 5 Sheets-Sheet 5 QC" fi24 Fig.4.

United States Patent poplars-unease UlRCUlT TERMEDHATE CQENTAQTS Charlesl3. Cromer, Leveigreen, Fa, to Westinghouse Electric Corporation, EastPittsburgh; Pa, a corporation of Pennsylvania Filed in, wet, Ser, No.325247 8 Claims. (Cl. Nth-148) This invention relates to circuitinterrupters in general, and more particularly, to circuit interruptersof the fluidblast type.

A general object of the present invention is to provide an improvedcircuit interrupter, particularly adaptable for high-power applicationand in which relatively high-rates of rise of recovery-voltage transientare encountered.

A more specific object of the present invention is to provide animproved interrupting structure for a highpower circuit interrupter inwhich the current, to be interrupted, is interrupted in two steps, thefirst step consisting of inserting an impedance, such as a resistance,serially into the circuit, and the second step consisting of breakingthe residual current by a series isolating break.

Another object or the invention is to provide an improvedcircuit-interrupting unit for a circuit breaker in which a fixed maincontact gap is obtained to prevent the accumulation of considerableionized gas, which would result if the gap were lengthened by continuedmovement of the movable contact structure.

Still a further object of the present invention is to provide animproved arc-extinguishing structure in which by a novel arrangement andconfiguration of the cooperable parts, considerably improvedarc-extinguishing action and consequent circuit interruption areobtained.

A further object of the present invention is the provision of animproved circuit-interrupting structure which is readily adaptable foruse either with a shunting impedance, such as a shunting resistance, oris adaptable for use omitting such a shunting impedance.

Another object of the invention is the provision of a circuitinterrupter of the type set forth in the immediately preceding paragraphin which the rte-arrangement of the interrupter may be accomplished witha minimum of effort.

Yet another object of the present invention is the provision of animproved gas-blast circuit interrupting unit, in which a relativelytubular intermediate contact structure is cooperable with the relativelystationary contact structure, and the blasting of gas may take placethrough the tubular intermediate contact structure to assist in thefinal interruption of the circuit at a series disconnecting break.

Further objects and advantages will readily become apparent upon readingthe following specification, taken in conjunction with the drawings, inwhich:

FIGURE 1 is an end elevational view of a multi-pole high-power circuitinterrupter embodying features of the present invention;

FIG, 2 is a longitudinal, sectional view taken through one of the tankstructures of the circuit interrupter of FIG. 1, illustrating theinternally-disposed arc-extinguishing assemblage, such assemblage beingillustrated in the closed-circuit position;

FIG. 3 is a considerably enlarged substantially vertical sectional viewtaken through the right-hand circuit-interrupting unit of thearc-extinguishing assemblage illustrated in FIG. 2, the contactstructure being illustrated in the fully open-circuit position; and,

FIG. 4 is a view similar to that of FIG. 3 but illustrating a modifiedtype of circuit-interrupting unit.

3,15%,726 Fatented Dec. 8, 1964 Referring to the drawings, and moreparticularly to FIG. 1 thereof, the reference numeral 1 generallydesignates a three-pole multi-phase, double-pressure cornpressed-gascircuit interrupter. FIG. 1 illustrates an end view of the structure,and consequently only the end tank 2 is shown. A mechanism housing 3 isdisposed at the end of the three breaker tanks 2 and encloses a suitableoperating mechanism, not shown, which is efiective to simultaneouslyactuate the arc-extinguishing assemblages 4 (PEG, 2) disposed interiorlyof the tank structures 2.

Extending downwardly interiorly within the tank structures 2 are pairsof terminal bushings 5, 6, which serve to carry the controlled circuitinto the tanks 2. The tanks 2 and the mechanism housing 3 are supportedupon steel beam 7 supported upon a concrete foundation 8. Preferably theends of the tanks 2 contain hinged covers 10, ill, which permitinspection within the tank structures 2.

With reference to FIG. 2 of the drawings, it will be observed thatsupported at the lower ends 12, 13, of the terminal bushings 5, 6,respectively, are support castings Me, 15, which fixedly support intoposition the arc-extinguishing assemblage 4.

The arc-extinguishing assemblage 4 generally comprises a plurality ofserially-related arc-interrupting units 16 of the gas-blast type, theconfiguration of which is more readily apparent from an inspection ofFIG. 3 of the drawings. Disposed adjacent the right-hand end of thearc-extinguishing assemblage is a high-pressure storage tank 17" Ablast-valve mechanism 18 is operable to control the blasting of gas outof the hi h-pressure storage tank 17 and toward the three gas-blastinterrupting units 16 to effect are extinction thereat.

The movable contact assemblage 20 generally comprises a pair of outerlongitudinally-extending insulating operating rods 21, which are bridgedby cross-bars 22 (FIG. 3), to the middle portions of which are fixedlysecured the movable isolating contacts 23, as shown more clearly in PEG.3. The rod-shaped isolating contact 23 makes engagement with a movabletubular intermediate contact structure 24, and forces the same againstspring pressure 25 t ward the right, as viewed in FIG. 3, and intoengagement with a relatively stationary contact structure, generallydesignated by the reference numeral 26. It will be observed, withreference to FIG. 3, that the relatively stationary contact structure 26comprises a cluster of finger contacts 27, and a centrally-disposedarcing horn In the closed-circuit position, indicated by the dottedlines 29, it will be observed that the arcing born 23 protrudesinteriorly within the tubular intermediate contact structure 24, so thatgood contacting engagement is provided by the fingers 27.

With further reference to FIG. 2, it will be noted that an openingaccelerating spring 31 biases the movable contact assemblage 2% towardthe left in an opening direction. This movement is resisted by thetension exerted by an operating rod 3;. formed of insulating material,and interconnecting the movable contact assemblage 2t? with an externaloperating mechanism disposed within mechanism compartment 3. Referencemay be had to United States patent application, filed January 23, 1959,Serial No. 788,668 by Russell N. Yeckley, loseph Sucha and Benjamin P.Baker, now Patent No. 3,057,983, and assigned to the assignee of theinstant application for a minute and detailed description of the severalparts associated with the circuit interrupter 1. For the purpose ofunderstanding the present invention,

however, it is only necessary to know that operation of the blast-valvemechanism 13 is operable to force the blast valve 33 (FIG. 3) toward theright, away from its seat 34 and permit the blasting of gas in thedirection indicated by the arrows 35. The gas blast not only blasts intothe first interrupting unit 116, but also passes down a plurality ofinsulating blast tubes 36, 37 and into the adjacent gas-blastinterrupting units 16 to effect are extinction therein. The arrangementis such that sufiicient gas-blast pressure exists simultaneously in allthree interrupting units 16 at the time of actual contact parting. As aresult, simultaneous extinguishing action is exerted Within each of theinterrupting units 16.

Reference may be had to U.S. patent application filed October 17, 1960,Serial No. 63,201 by Russell N. Yeckley, Joseph Sucha and Roswell C. VanSickle, and assigned to the assignee of the instant application for adescription of the blast-valve mechanism 118. The operation of thisblast-valve mechanism 18 forms no part of the present invention andconsequently a description thereof is deemed unnecessary.

With reference to FIG. 2 of the drawings, it Will be observed that apair of insulating tie-bars 39 mechanically interconnect the end clampcastings 14, 15, and serve to fixedly secure into proper position thestationary contact structure 26, associated with each of the gas-blastinterrupting units 16. In addition, it will be observed that thestationary contact structures 26, associated with the middle andleft-hand interrupting units 16, contain rightwardly-extendingrelatively stationary contact fingers 40, which serve to guide theadjacently-disposed movable contacts 23, and to carry current therefromto the adjacent stationary contact structure 26 of the adjacent unit 16.

During the opening operation, the mechanism, not shown, disposedinteriorly within the mechanism housing 3 is unlatched to thereby permitthe crank-shaft 43 to rotate in a clockwise direction. Because of thebiasing action exerted by the opening accelerating spring 3 1, theentire movable contact assemblage 20, comprising a plurality of themovable contacts 23, interconnected by the insulating tie-bars 21, willmove as a unit, toward the left in a circuit-opening direction. Withreference to PEG. 3, it will be observed that the presence of thecompression spring 25 will force the intermediate contact structure 24toward the left maintaining contact with the movable isolating contact23. Upon separation between the arc-resisting tip portion 30 of thetubular intermediate contact 24 from the stationary contact fingers 27,a maincurrent are 44 will be established, and will quickly transfer,because of the gas blast, to the arcing horn 28 and the inner surface 45of the tubular intermediate contact 24.

To facilitate the interruption of heavy current, and also to assist inthe interruption of circuits having high rates of rise of recoveryvoltage, a shunting impedance, generally designated by the referencenumeral 46, and comprising a resistance tube 47, is inserted seriallyinto the circuit. An alternate construction could be a helicalresistance wire winding, or even stacked resistance rings could be used.The material of the resistance rings could be filled with carbongranules and a suitable binder for the requisite resistance value. Thiswill assist in the interruption of the main-current are 44 and willimprove the power factor of the circuit after insertion into thecircuit. The insertion of the resistance modifies the voltage recoverytransient of the main gap.

The movable tubular intermediate contact structure 24- will move to theleft until the flange portion 48 thereof strikes a fixed stop 50establishing a fixed gap between the stationary contact 26 and thetubular contact 24. The disconnecting contact 23 does not necessarilybreak immediately. It could, and perhaps should stay in engagement untilthe main arc 44 has been completely interrupted in the main gap to avoidunnecessary burning and arc products. The maximum arcing time in themain gap would then determine the overlap between disconnecting contact23 and intermediate fingers 53. A residual current arc, designated bythe reference numeral 52, will finally be established between thedisconnecting contact 23 and intermediate contact 24. Because of theimprovement in the power factor of the circuit, and also because themagnitude of the current has been considerably diminished by theinsertion of the impedance 47 into series circuit, the interruptioneffort required to interrupt the residual current are 52 is relativelyslight. In this connection, it will be observed that the gas blastpasses centrally down through the tubular intermediate contact 24 andassists in the interruption of the residual current are 52.

As viewed in FIG. 3, it will be noted that a plurality of segmentalintermediate current fingers 53 are provided, being biased radiallyinwardly by compression springs 54 to provide good contacting pressurebetween the contacts 23 and 53 in the closed-circuit position of theinterrupter. In addition, the segmental contact fingers 53 preferablyhave an arc-resisting tip portion 55 to resist the eroding actionexerted by the are 52.

As stated hereinbefore, the residual current are 52 is quicklyinterrupted by the gas blast passing interiorly through the movableintermediate contact 24, and circuit interruption is thereby quicklybrought about. The movable disconnecting contact 23 continues to move toa fully-open isolating position, as indicated by the fully open-circuitposition of the interrupter in FIG. 3. Merely for the purpose ofillustrating the invention have the main-current and residual-currentarcs 44, 52 been drawn into the illustration of FIG. 3, although it mustbe remembered that the contact parts are illustrated in the fullyopen-circuit position of the interrupter 11.

As the power requirements of the utilities continue to grow, themagnitude of fault currents considerably increases. This is accompaniedby higher current values and also high rates of rise of recovery voltagetransients. Furthermore, emphasis is being placed more on line faults,in which the rate of rise of recovery voltage can become very severe,and it is desirable to modify interrupting structures to enable them tointerrupt such high rates of rise of recovery voltage with lessdifficulty.

It has been demonstrated experimentally that interrupting times can bedecreased by forcing the are into the hollow moving contact of thecircuit breaker at short arc lengths or at short gaps between the movingcontact and the relatively stationary arcing horn, and thus performingits interrupting function. However, for successful interruptions ofcapacitive currents, speed is of prime importance, which means that thecontacts must have a maximum separation and maximum creepage onehalfcycle after parting.

It is evident that as the arc lengthens and the current is increased,more and more are products are formed and greater thermal expansion ofthe gases occur. As a result, the discharge nozzle becomes clogged andan interrupting limit is reached. This means that the orifice must beincreased in diameter or the driving pressure increased, or bothneitherof which is desirable for compact arrangements.

The present invention proposes an improved interrupting construction inwhich:

(1) The arc length or contact separation is not random, but fixed at apredetermined maximum, assuring thereby a minimum amount of are productsand thermal expansion, which, in turn, provides for a reduction innozzle diameter and more compact assembly.

(2) An impedance, such as a resistor, shunt to modify the rate of riseof recovery voltage.

(3) An auxiliary contact to interrupt the resistor current.

The interrupting unit 16 consists essentially of a firstbreak stationaryfinger contact and arcing horn assembly 26, intermediate movable contactassembly 24, a resistor shunt assembly 46, and a movable disconnectingcontact assembly 23.

FIG. 3 shows the contact structure in the fully opencircuit position. Toclose the contacts, the moving con tact rod 23 moves toward the right,and the circuit is made up through the resistor 47 when thedisconnecting contact 23 engages the finger assembly 53. This move mentcontinues until the overlap position of the intermediate contact 24reaches the dot-dash line 29 of FIG. 3. In the fully closed position,the main interrupting contact assembly is biased toward the open circuitposition by the compression spring 25, which is confined between themain interrupting contact 24 and the blast shield assembly 55. The blastshield assembly 56 comprises the guide 57 and the stop 5%. This assemblyis, in turn, mounted to the tie-bar rods 39 and maintained in a fixedposition. The insulating guide nozzle 5'3 performs a dual function ofnot only acting as a close-fitting, lowfriction insulating guide, butalso acts as a closure member to direct the gas flow through the tubularintermediate contact assembly 24.

During the opening operation, both contact assemblies 23, 24 withdrawtogether as a unit, until the intermediate contact assembly 24 strikesthe stop St). The compression spring 25 not only provides sufiicientforce to accelerate the intermediate contact assembly 24 but also actsas an initial high-force, kick-off spring, for the breaker. The movablecontact assembly 23 continues to move, and just prior to parting withthe finger contacts 53 will have traveled in the order of four or fiveinches, for example, which should allow ample time to interrupt the maincurrent arc 44, and make the circuit transfer through the resistorassembly 47.

The transfer of the main current into the resistor as sembly 4'7 takesplace in the following manner: The main current are 44, drawn betweenthe relatively stationary contact 26 and the tubular intermediatecontact assembly 24, is blasted into the expanding tubular contact 24.At current Zero, this blast establishes sufficient dielectric totransfer the electrical circuit through the resistor 47 and maintainadequate strength to prevent re-ignition. The are products are swept outof the arc region down the tubular intermediate contact 24 and out ofthe lateral ports 60. The blast-shield assembly 56 prevents any hotgases from impinging on insulating surfaces.

As the contact assembly 23 continues to move toward the open position itdraws a residual-current are 52 between the contacts 23, 53. Thisresistor current is very low in value, say 200 to Silt) amperes, forexample, and is easily interrupted by even a very slight gas flow downthe tubular contact 24.

FIG. 4 illustrates a modified type of interrupting unit 61 in which theimpedance shunt 46 is omitted. it has been noted on tests that wheninterrupting very high currents, the interrupting times varied from 2.5cycles to 2.9 cycles. It appears that the breaker will not interrupt at2.4 cycles, which has a relatively short gap (less than one inch), butwill interrupt each time at the 2.5 cycle position (in the order of 1 to1 /2 inch gap). At 2.9 cycles the gap has become quite long(approximately 2.8 inches) and the interrupter, due to arc products, maystart clogging and possibly fail if interruption of higher currentvalues are attempted. It is, therefore, of no advantage, and becomessomewhat disadvantageous to draw a long main current are.

If the moving contact is stopped at some optimum gap, say 1.5 inches,then the 2.4 cycle position can be passed without lengthening the gap tosome excessive value. Since interruption in some circuits can be madewithout aid of a shunting resistor, under certain circuit conditions,the modified interrupter construction 61 of FIG. 4 is advantageous inthat the resistor 47 is omitted, and yet the main contact gap distanceis set at the optimum value. Without the employment of the shuntingresistor 47, the moving contact 23 becomes merely an isolating breakWith no interrupting function to perform. The opening and closingoperations would remain the same as described above in connection withthe interrupter unit 16 of FIG. 3.

From the foregoing description of the invention, it

will be apparent that there is provided an improved interrupterconstruction 16 embodying a relatively stationary contact structure 26,an intermediate contact structure 24 and a movable disconnecting contactstructure 23. Particularly advantageous results are achieved by the useof a tubular intermediate contact structure 24, through which the gasblast may be exhausted and facilitate interruption of the residualcurrent are 52.

For certain applications it is advantageous to eliminate the shuntingresistance 47 and to maintain the main gap distance at an optimum valueas illustrated in FIG. 4.

Certain features of the orifice construction for the interrupting unit16 are set forth and claimed in US. Patent Application, filed October 7,1960, Serial No. 61,284 by Robert G. Colclaser and Russell N. Yeckley,and assigned to the assignee of the instant application.

Although there have been illustrated and described specific structures,it is to be clearly understood that the same were merely for the purposeof illustration, and that changes and modifications may readily be madetherein by those skilled in the art, without departing from the spiritand scope of the invention.

I claim as my invention:

1. A gas-blast interrupting unit for a circuit interrupter including arelatively stationary contact, a movable tubular intermediate contactseparable from said relatively stationary contact to establish amain-current arc, an impedance shunted across the stationary andintermediate contacts, means including a relatively tight-fittinginsulating orifice member about the intermediate contact for defining apressure chamber about the relatively stationary contact, a source ofgas pressure, means for admitting at times compressed gas from saidsource into said pressure chamber whereby a blast of gas issubstantially wholly forced through the tubular movable intermediatecontact to extinguish said main-current are, a movable isolating contactcooperable with the intermediate contact to establish a residual-currentarc, and the blast of gas forced through the tubular movableintermediate contact being used not only to extinguish the maincurrentare, but, additionally, the same gas being used, at least in part, toextinguish said residual-current arc.

2. A gas-blast interrupting unit for a circuit interrupter including arelatively stationary contact, a movable tubular intermediate contactseparable from said relatively stationary contact to establish amain-current are, an impedance shunted across the stationary andintermediate contacts, means defining a stop for opening movement of thetubular intermediate contact, means including a relatively tight-fittinginsulating orifice member about the intermediate contact for defining apressure chamber about the relatively stationary contact, a source ofgas pressure, means for admitting at times compressed gas from saidsource into said pressure chamber whereby a blast of gas issubstantially wholly forced through the tubular movable intermediatecontact to assist in extinguishing the main-current arc, a movableisolating contact cooperable with the intermediate contact to establisha residual-current arc, and the blast of gas forced through the tubularmovable intermediate contact not only being used to effect extinction ofthe main-current arc, but, additionally, being used at least in part toextinguish said residual-current are.

3. The gas-blast interrupting unit according to claim 2, wherein biasingmeans are provided for biasing the intermediate contact to theopen-circuit position.

4. A gas-blast interrupting unit for a circuit interrupter including arelatively stationary contact, a movable tubular intermediate contactseparable from said relatively stationary contact to establish amain-current arc, an impedance shunted across the stationary andintermediate contacts, said tubular intermediate contact having anannular flange portion and segmental fingers at one end thereof, meansincluding a relatively tight-fitting insulating orifice member about theintermediate contact for defining a pressure chamber about therelatively stationary contact, a source of gas pressure, means foradmitting at times compressed gas from said source into said pressurechamber whereby gas may be forced through the tubular intermediatecontact to effect extinction of said main-current arc, and a movableisolating contact cooperable with the intermediate contact to establisha residual-current arc.

5. The combination in a gas-blast interrupting unit of a relativelystationary contact structure, a movable tubular intermediate contactseparable from said relatively stationary contact structure to establisha main-current arc, said movable tubular intermediate contact having aflange portion and side vent openings, an enclosing blast shield, acompression spring seated on said flange and against one end of saidblast shield, a shunting impedance electrically connected between thestationary and intermediate contacts, means including a relativelytight-fitting insulating orifice member about the intermediate contactfor defining a pressure chamber about the relatively stationary contact,a source of gas pressure, means for admitting at times compressed gasfrom said source into said pressure chamber whereby a blast of gas issubstantially Wholly forced through the tubular movable intermediatecontact, and a movable disconnecting contact cooperable with saidintermediate contact to establish a residual-current are.

6. The gas-blast interrupting unit according to claim 1,

3 wherein the movable tubular intermediate contact has side ventopenings therein.

7. A gas-blast interrupting unit according to claim 1, wherein stopmeans are provided so that the arcing tip portion of the movable tubularintermediate contact al- Ways remains Within the pressure chamber aboutthe relatively stationary contact.

8. A gas-blast interrupting unit according to claim 1, wherein the endof the tubular movable intermediate contact is provided withintermediate fingers making overlapping contacting engagement with themovable isolating contact, whereby assurance is obtained that themaincurrent are Will be extinguished prior to the establishment of aresidual-current arc.

References Cited in the file of this patent UNITED STATES PATENTS2,075,749 Paul Mar. 30, 1937 2,117,261 Thommen May 10, 1938 2,146,685Prince Feb. 7, 1939 2,293,320 Thommen Aug. 18, 1942 2,757,261 Lingal etal. July 31, 1956 FOREIGN PATENTS 610,946 Germany Mar. 19, 1935

1. A GAS-BLAST INTERRUPTING UNIT FOR A CIRCUIT INTERRUPTER INCLUDING A RELATIVELY STATIONARY CONTACT, A MOVABLE TUBULAR INTERMEDIATE CONTACT SEPARABLE FROM SAID RELATIVELY STATIONARY CONTACT TO ESTABLISH A MAIN-CURRENT ARC, AN IMPEDANCE SHUNTED ACROSS THE STATIONARY AND INTERMEDIATE CONTACTS, MEANS INCLUDING A RELATIVELY TIGHT-FITTING INSULATING ORIFICE MEMBER ABOUT THE INTERMEDIATE CONTACT FOR DEFINING A PRESSURE CHAMBER ABOUT THE RELATIVELY STATIONARY CONTACT, A SOURCE OF GAS PRESSURE, MEANS FOR ADMITTING AT TIMES COMPRESSED GAS FROM SAID SOURCE INTO SAID PRESSURE CHAMBER WHEREBY A BLAST OF GAS IS SUBSTANTIALLY WHOLLY FORCED THROUGH THE TUBULAR MOVABLE INTERMEDIATE CONTACT TO EXTINGUISH SAID MAIN-CURRENT ARC, A MOVABLE ISOLATING CONTACT COOPERABLE WITH THE INTERMEDIATE CONTACT TO ESTABLISH A RESIDUAL-CURRENT ARC, AND THE BLAST OF GAS FORCED THROUGH THE TUBULAR MOVABLE INTERMEDIATE CONTACT BEING USED NOT ONLY TO EXTINGUISH THE MAINCURRENT ARC, BUT, ADDITIONALLY, THE SAME GAS BEING USED, AT LEAST IN PART, TO EXTINGUISH SAID RESIDUAL-CURRENT ARC. 